ABSTRACT
Parkinson's disease (PD) is a progressive neurodegenerative disorder, ones of the main symptoms of which are hypertonicity and emergent difficulties during performance of stepping movements due to increased muscle stiffness. Biomechanical (stiffness) and electrophysiological (shorting reaction) characteristics of hip and shank muscles were examined in 25 patients with mild and moderate stages of PD (1 to 3 of Hoehn & Yahr Rating Scale, 61 +/- 9 years) and 22 age-matched healthy controls in unloading leg conditions during passive flexion/extension of hip, knee and ankle joints, as well as the changes of tonic state under levodopa influence. The data obtained were compared with similar findings of healthy subjects. Essentially greater stiffness in all leg muscle groups (with the exception of foot extensors) were observed in patients as compared with healthy. During passive movements the shorting reactions (SR) in hip and shank muscles were often observed, in healthy subjects the SR were observed more rarely. In patients with PD the values of SR in extensors of hip and shank, as well as in flexor and extensor muscles of foot were essentially greater then in healthy. The medicine essentially reduced the stiffness of hip flexors and flexors and foot extensors. The SR were persisted but the frequency of its appearance was decreased in half of investigated muscles, and significant decreasing of SR amount was observed in extensors of foot. The medicine did not exert influence upon SR in proximal muscles. Thus, increasing muscle stiffness in patients with PD is manifested in uncorrected reactions on external disturbances and reflected in increasing of reflectory reaction of muscles.
